Preparation and properties of SiO2-Al2O3 composite aerogels

doi:10.3969/j.issn.1001-1935.2025.05.005

Abstract

Abstract: To improve the performance of SiO₂-Al₂O₃ aerogels and expand their application field at high temperatures,SiO₂-Al₂O₃ composite aerogels were prepared by the sol-gel method followed by ambient pressure drying,adopting ethyl orthosilicate as the silicon source,aluminum chloride hexahydrate as the aluminum source,water and ethanol as the solvent,and trimethylchlorosilane/n-hexane as the modifier.The effects of n(Si)∶n(Al) (2∶1,1∶1,1∶2,1∶3 and 1∶4) on the gelling time,microstructure,specific surface area and thermal conductivity of the composite aerogels were studied.On this basis,the SiO₂-Al₂O₃ composite aerogels were heat treated at different temperatures (600,800,1 000,1 100 and 1 200 ℃) for 2 h,and then characterized and analyzed by SEM,XRD,BET,TG-DSC,and FT-IR.The results show that:(1)when n(Si)∶n(Al)=1∶3,the SiO₂-Al₂O₃ composite aerogel has the best performance,the gelling time is 7.64 min,and the specific surface area is 397 m²·g^-1;(2)SiO₂ in the composite aerogel inhibits the crystal transformation of Al₂O₃,and the gel network formed by Al—O—Si bond improves the strength,thermal stability and high temperature thermal insulation performance of the aerogel;(3)when n(Si)∶n(Al)=1∶3,after the heat treatment at 1 200 ℃,α-Al₂O₃ is not detected in the SiO₂-Al₂O₃ composite aerogel,and the porous structure still maintains intact,and its thermal conductivity at room temperature is 0.053 W·m^-1·K^-1。

Key words: SiO₂-Al₂O₃ composite aerogel, sol-gel method, ambient pressure drying, heat treatment, thermal stability

摘要： 为了提高SiO₂-Al₂O₃气凝胶性能,拓展其在高温下的应用领域,以正硅酸乙酯为硅源、六水氯化铝为铝源、水和乙醇为溶剂、三甲基氯硅烷/正己烷为改性剂,采用溶胶-凝胶法通过常压干燥制备SiO₂-Al₂O₃复合气凝胶。研究了Si、Al物质的量比(2∶1、1∶1、1∶2、1∶3和1∶4)对复合气凝胶凝胶时间、显微结构、比表面积、热导率等的影响。在此基础上,对SiO₂-Al₂O₃复合气凝胶分别进行600、800、1 000、1 100、1 200 ℃保温2 h热处理,并利用SEM、XRD、BET、TG-DSC、FI-IR等手段对热处理后复合气凝胶进行表征和分析。结果表明:1)当n(Si)∶n(Al)=1∶3时,制得SiO₂-Al₂O₃复合气凝胶性能最佳,其凝胶时间为7.64 min,比表面积为397 m²·g^-1;2)复合气凝胶中的SiO₂抑制了Al₂O₃的晶型转变,Al—O—Si键形成的凝胶网络提高了气凝胶的强度、热稳定性和高温隔热性能;3)当n(Si)∶n(Al)=1∶3,经1 200 ℃热处理后,SiO₂-Al₂O₃复合气凝胶未出现 α-Al₂O₃,仍保持完整的多孔结构,其室温热导率为0.053 W·m^-1·K^-1。

关键词: SiO₂-Al₂O₃气凝胶, 溶胶-凝胶法, 常压干燥, 热处理, 热稳定性

CLC Number:

TB332

Wang Zhizheng, Guo Yuxiang, Wang Xin, Yang Bo, Sun Peisong, Zhang Fengchuang. Preparation and properties of SiO₂-Al₂O₃ composite aerogels[J]. Refractories, 2025, 59(5): 391-397.

王指正, 郭玉香, 王鑫, 杨博, 孙培凇, 张风闯. SiO₂-Al₂O₃复合气凝胶的制备及其性能研究[J]. 耐火材料, 2025, 59(5): 391-397.

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Preparation and properties of SiO₂-Al₂O₃ composite aerogels

SiO₂-Al₂O₃复合气凝胶的制备及其性能研究

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